Certain imidazolinyl benzoic and naphthoic acids, esters and salts and their use as herbicidal agents are described in U.S. Pat. Nos. 4,188,487; 4,297,128 and 4,554,013 and in patent applications GB 2 172 866 A and EP 86200304.3. However, the imidazolinyl benzoheterocycles of the present invention are not described nor suggested in said patents and patent applications. Fused heteropyridine compounds and their herbicidal use are described in U.S. Pat. Nos. 4,650,514 and 4,752,323 and copending U.S. application Ser. No. 465,569 filed on Jan. 16, 1990. Although a variety of herbicidally active imidazolinyl compounds are known, still more effective imidazolinyl compounds would be useful to farmers, agriculturalists, industrialists and the like for the control of undesirable plant species.
It is an object of the present invention to provide effective herbicidal imidazolinyl o-carboxy-2-benzoheterocyclic compounds and indoloheterocyclic diones for controlling a variety of monocotyledenous and dicotyledenous plant species such as those species which are generally difficult to control in agronomic practice.